Why Spark Plug Selection Matters
The spark plug is one of the most fundamental components in a gasoline engine. It ignites the air-fuel mixture in each cylinder, thousands of times per minute. Choosing the right spark plug ensures reliable starts, smooth idle, optimal fuel economy, and long engine life. The wrong plug — or a worn one — can cause misfires, rough running, and even engine damage over time.
Spark Plug Types: What Are Your Options?
Copper Core Spark Plugs
Copper-core plugs are the original standard. They have a solid copper center electrode and excellent conductivity. The downside: copper is softer than platinum or iridium, so these plugs wear faster and typically need replacement every 20,000–30,000 miles. They're a great choice for older vehicles with distributor-based ignition systems, and they cost less upfront.
Platinum Spark Plugs
Platinum plugs use a platinum disc welded to the center electrode tip. Platinum is much harder than copper and resists erosion better, extending service life to around 60,000 miles. Double-platinum plugs (platinum on both electrodes) are used in waste-spark ignition systems where both electrodes fire. ACDelco and NGK both produce quality platinum plugs for a wide range of vehicles.
Iridium Spark Plugs
Iridium is the hardest material used in spark plug manufacturing. Iridium plugs feature an ultra-fine center electrode (sometimes just 0.4mm in diameter), which requires less voltage to fire and creates a more precise, powerful spark. They last up to 100,000 miles in many applications. NGK Iridium IX, NGK Laser Iridium, Champion Iridium, and Autolite Iridium XP are all popular choices for modern engines.
How to Find the Right Plug for Your Vehicle
Every vehicle manufacturer specifies an exact plug type by part number. You can find your correct spark plug by:
- Your owner's manual: The maintenance section lists the OEM plug specification.
- Cross-reference charts: NGK, Champion, and Autolite publish cross-reference guides that match competitor part numbers to their equivalents.
- Vehicle lookup: Most auto parts stores (and our store) allow you to search by year, make, model, and engine size.
Key Specs to Match
When selecting a spark plug, always verify these specifications:
- Thread diameter and pitch (e.g., 14mm x 1.25)
- Reach (threaded length that enters the cylinder head)
- Heat range (how quickly the plug dissipates heat — critical for performance)
- Gap (distance between center and ground electrodes — always verify against your vehicle's spec)
- Seat type (tapered or gasket/flat)
When Should You Replace Spark Plugs?
General replacement intervals by plug type:
- Copper plugs: every 20,000–30,000 miles
- Platinum plugs: every 60,000 miles
- Double-platinum plugs: every 60,000 miles
- Iridium plugs: every 60,000–100,000 miles
Always replace plugs sooner if you experience misfires, hard starting, rough idle, or a drop in fuel economy.
Shop Spark Plugs at Texan Supply Company
We carry a full range of spark plugs from NGK, Champion, ACDelco, and Autolite — including copper, platinum, and iridium options for virtually every vehicle on the road. Shop our NGK collection, Champion collection, and Autolite collection to find the perfect plug for your vehicle.